The default split is 1.5 GB I believe, give or take.  You can increase that in later version of DA.

Export from Discovery Accelerator (DA) to Personal Store (PST) file results in a maximum PST file size of 1.5GB

• Article: TECH199693
• Updated: May 19, 2014
• Article URL: http://www.symantec.com/docs/TECH199693

Problem

In Microsoft Outlook 2002 and previous versions the maximum allowed size for a PST file was set at 2GB. A certain amount of corruption protection has been implemented and PST files created as part of the DA export process are limited to a maximum size of 1.5GB. In post Outlook 2002 versions the PST format changed from ANSI to Unicode and subsequently the maximum allowable file size for a Unicode PST file is set to 20GB. (This can be increased to 50GB via a registry key).

When exporting data from DA to a Unicode PST there is still a coded limit of 1.5GB and there is currently no way for a DA export to be split into larger PST file sizes.

Solution

This issue has been addressed in the following release:

Enterprise Vault 10.0.4 Cumulative Hotfix 3 Release
http://www.symantec.com/docs/TECH215093

Symantec Enterprise Vault 11.0 0 Release Details
http://www.symantec.com/docs/DOC7401

Applies To

All versions of Discovery Accelerator.